In an electronic or electrical circuit using an inductive load (inductance), signals input to the inductive load generate voltage by electromagnetic induction even across an adjacent metal part insulated from the inductive load. Such induced voltage varies according to signals input to the inductive load. A potential difference caused by induced voltage generates current flow. Such induced current or voltage, which may cause an electric shock, is unnecessary for the operation of the electrical circuit and thus is removed by the grounding method in conventional electrical circuits (see Patent Literature 1, for example).